Format

Send to

Choose Destination
Biophys J. 2014 Mar 18;106(6):1406-13. doi: 10.1016/j.bpj.2014.02.012.

Porosity controls spread of excitation in tectorial membrane traveling waves.

Author information

1
Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge, Massachusetts; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts.
2
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts.
3
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts.
4
Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
5
Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge, Massachusetts; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts. Electronic address: freeman@mit.edu.

Abstract

Cochlear frequency selectivity plays a key role in our ability to understand speech, and is widely believed to be associated with cochlear amplification. However, genetic studies targeting the tectorial membrane (TM) have demonstrated both sharper and broader tuning with no obvious changes in hair bundle or somatic motility mechanisms. For example, cochlear tuning of Tectb(-/-) mice is significantly sharper than that of Tecta(Y1870C/+) mice, even though TM stiffnesses are similarly reduced relative to wild-type TMs. Here we show that differences in TM viscosity can account for these differences in tuning. In the basal cochlear turn, nanoscale pores of Tecta(Y1870C/+) TMs are significantly larger than those of Tectb(-/-) TMs. The larger pore size reduces shear viscosity (by ∼70%), thereby reducing traveling wave speed and increasing spread of excitation. These results demonstrate the previously unrecognized importance of TM porosity in cochlear and neural tuning.

PMID:
24655516
PMCID:
PMC3984983
DOI:
10.1016/j.bpj.2014.02.012
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center